From 7708b88c3078c5ec9750769b293179513dd57eb8 Mon Sep 17 00:00:00 2001
From: patsonluk <patson@fullstory.com>
Date: Fri, 15 Sep 2023 15:01:08 -0700
Subject: [PATCH] Log refCount and core name if refCount of SolrCore is > 1
 after SolrDispatchFilter finishes processing it.

---
 .../org/apache/solr/servlet/SolrDispatchFilter.java | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/solr/core/src/java/org/apache/solr/servlet/SolrDispatchFilter.java b/solr/core/src/java/org/apache/solr/servlet/SolrDispatchFilter.java
index cfd9836c4ed..36ba8694cf9 100644
--- a/solr/core/src/java/org/apache/solr/servlet/SolrDispatchFilter.java
+++ b/solr/core/src/java/org/apache/solr/servlet/SolrDispatchFilter.java
@@ -49,6 +49,7 @@
 import org.apache.solr.common.util.SuppressForbidden;
 import org.apache.solr.core.CoreContainer;
 import org.apache.solr.core.NodeRoles;
+import org.apache.solr.core.SolrCore;
 import org.apache.solr.handler.api.V2ApiUtils;
 import org.apache.solr.logging.MDCLoggingContext;
 import org.apache.solr.logging.MDCSnapshot;
@@ -275,6 +276,18 @@ private void dispatch(
       }
     } finally {
       call.destroy();
+      SolrCore core = call.getCore();
+      if (core != null) {
+        int coreRefCount = core.getOpenCount();
+        if (coreRefCount > 1) {
+          if (log.isInfoEnabled())
+            log.info(
+                "Core {} has ref count of {} . It's still used by other logic even if the current servlet request {} finishes",
+                core.getName(),
+                coreRefCount,
+                call.getReq().getServletPath());
+        }
+      }
       ExecutorUtil.setServerThreadFlag(null);
     }
   }